This invention relates to a liquid dispenser and is particularly useful as a dispenser for toilet bowl cleaners, though it can be used in other installations where liquid is to be dispensed into water or some other liquid, and in which the liquid acts as a buoying force for holding the dispenser in a normally closed position and causes the liquid to be dispensed into the water when the water level drops.
Dispensers for toilet bowl cleaners have normally operated on a different principle, namely, the principle of having the buoying force of the water in the tank cause dispensing of the charge and therefore to mix the toilet bowl cleaner with the contents of the tank at the time when the tank has just been filled. When the tank is emptied by flushing, no further dispensing takes place until the tank is once again nearly full, at which time the next dispensing takes place.
One of the disadvantages of this prior-art type of operation is that the material is dispensed into water filling the entire toilet tank, and the diluted solution remains there, possibly for long periods of time. Also, the eventual solution is so dilute that more material may be required than would be the case where the dispensing can be done at the time of flushing and after the water level has dropped enough so that a relatively concentrated charge of diluted solution is available for cleaning the toilet bowl during the only time that the material is really acting as a cleaner. So long as the liquid being dispensed is one which diffuses itself very rapidly into the water in the tank there is nothing to be gained by dispensing it long before it it used, and the loss in concentration is certainly of no benefit.
Therefore, one object of the present invention is to enable one to obtain better cleaning action with even less fluid by dispensing it at a time when it can act in a stronger more concentrated solution during the relatively brief interval when the solution performs its cleaning action.
The present invention may be considered to be an improvement over U.S. Pat. No. 3,841,524, and acts on the same basic principle. However, it does so with fewer parts and with better and surer action. Also, its manufacture requires fewer molds and results in simplifying assembly. Furthermore, it is less expensive to manufacture even though it obtains better results.
A device operating in the same basic manner as U.S. Pat. No. 3,841,524 is shown in U.S. Pat. No. 3,908,209, issued to William E. Fillmore. This device comprises three elements and meters the fluid it dispenses in such a way that the heavy viscous liquid cannot be repeatedly measured accurately, some of it tending to remain in the metering chamber, partly because it tends to plug narrow passageways therebelow and thereby to prevent adequate access of air to the metering chamber. Also, the Fillmore device requires a very large bottle cap and fails to provide the required resiliency needed for the operating parts in order to seal the bottle adequately when capped. Other difficulties with Fillmore are also solved by the present invention which has further advantages also, discussed below.